Interactive effects of elevated CO2, O3, and soil water deficit on spring wheat (Triticum aestivum L. cv. Nandu)

摘要

The interactive effects of elevated carbon dioxide (CO2), ozone (O3), and soil water deficit were examined in spring wheat (Triticum aestivum cv. Nandu). Plants were grown in open-top chambers (OTCs) which were arranged in a 2X2 factorial design consisting of two O3 levels (ambient and 1.5-times ambient) in combination with two CO2 levels (ambient and ambient plus 320μmol/mol CO2). Subplots in each OTC were subjected to two levels of watering, well-watered and restricted water supply. Total leaf conductance (gL), growth and biochemical analyses were determined to assess plant responses. The relative reduction in gL due to CO2, soil water deficit and/or O3 depended on plant growth stage. However, complex interactions between the experimentally controlled factors occurred on many days. Reduced water supply resulted in growth reduction but provided some protection against the loss in dry weight caused by O3. Elevated CO2 stimulated plant growth, but no interactive effects between CO2, soil water deficit and/or O3 were observed, suggesting that elevated CO2 reduced the adverse effects of O3 and/or soil water deficit in an additive manner. The complex nature of the multiple stress interactions involved was also illustrated by the responses of specific biochemical variables (carbohydrates, proline, pigments).